Snap action switch mechanism



1966 J. o. ROESER 3,283,596

SNAP ACTION SWITCH MECHANISM Filed Aug. 21, 1964 5 Sheets-Sheet 1 INVENTOR. John 0. Roeser Nov. 8, 1966 J. o. ROESER 3,283,596

sNAP ACTION SWITCH MECHANISM Filed Aug. 21, 1964 5 Sheets-Sheet 2 John 0. Roeser aZ/wMZ Nov. 8, 1966 J. o. RoEsER SNAP ACTION SWITCH MECHANISM 5 Sheets-Sheet 5 Filed Aug. 21, 1964 SNAP ACTION SWITCH MECHANISM Filed Aug. 21, 1964 I 5 Sheets-Sheet 4 5 I f E. S l d in J i 50 J54 J55 55 44a; 4000 15660 361- 145 4186i 145 40d INVENTOR. John 0. Roe ser Nov. 8, 1966 J. o. ROESER SNAP ACTION SWITCH MECHANISM 5 Sheets-Sheet 5 Filed Aug. 21, 1964 5 E /f5 9M J74 I75 JM INVENTOR. John 0. Raeser United States Patent 3,283,596 SNAP ACTION SWITCH MECHANISM John 0. Roeser, Park Ridge, 11]., assignor to Illinois Tool Works Inc., Chicago, 11]., a corporation of Delaware Filed Aug. 21, 1964, Ser. No. 391,088 6 Claims. (CI. 74-54) This invention is concerned with the art of electric switches, and more particularly with a detent locking mechanism and cooperating spring drive for insuring a snap movement from one osition to another.

It is well known that it is undesirable to have switches open and close their contacts slowly, as this causes arcing with resultant burning of the contacts and sometimes damage to related devices. Various types of snap switch mechanisms have been developed to insure rapid opening and closing of the switch contacts. This invention relates to a switch of the snap switch type, and more particularly to improved operating parts therefor.

It is an object of this invention to provide a superior snap switch mechanism.

It is another object of this invention to provide a snap switch mechanism which is compact and yet rugged.

A further object of this invention is to provide a snap switch mechanism operable over a great number of switch positions.

It is a further object of this invention to provide a rotary snap switch mechanism.

A still further object of this invention is to provide a snap switch mechanism converting rotary motion to reciprocating motion for operating switches of the low travel or push button type.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings, wherein:

FIG. 1 is an elevational view of a preferred embodiment of the invention;

FIG. 2 is a cross sectional view thereof as taken substantially along the line 22 in FIG. 1;

FIG. 3 is a longitudinal sectional view on an enlarged scale through the operating mechanism, and corresponding to part of FIG. 1;

FIG. 4 is a view similar to FIG. 3 showing the parts in a different position of operation;

FIG. 5 is a cross sectional view taken along the line 55 in FIG. 3;

FIG. 6 is a cross sectional view along the line 66 in FIG. 3;

FIG. 7 is an exploded perspective view of the detent operating mechanism of the snap switch;

FIG. 8 is a fragmentary detail view showing the cam of the driver or driving plate;

FIG. 9 is a view similar to FIG. 5 showing a modification of the invention;

FIG. 10 is an exploded perspective view corresponding to FIG. 7 and showing the modification of FIG. 9;

FIG. 11 is a plan view of the driver or driving plate of the modification;

FIG. 12 is a fragmentary longitudinal view through a modified form of the invention;

FIG. 13 is a longitudinal sectional view through another modification of the invention as taken substantially along the line 1313 in FIG.

3,283,596 Patented Nov. 8, 1966 ICC FIG. 14 is a cross sectional view taken along the line 1414 in FIG. 13;

FIG. 15 is a fragmentary cross sectional view taken substantially along the line 1515 in FIG. 13;

FIG. 16 is a fragmentary longitudinal sectional view taken substantially along the line 1616 in FIG. 15;

FIG. 17 is a front view of an encased. modified switch unit;

FIG. 18 is a side view thereof;

FIG. 19 is a top view with the case or housing removed;

FIG. .20 is a vertical sectional view taken substantially along the line 2tt20 in FIG. 19;

FIG. 21 is a vertical longitudinal sectional View along the line 21-21 in FIG. 17;

FIG. 22 is a vertical cross sectional view along the line 2222 in FIG. 21;

FIG. 23 is a vertical cross sectional view along the line 2323 in FIG. 20;

FIG. 24 is a vertical cross sectional view looking to ward the front of the switch unit substantially along the line 2424 in FIG. 21;

FIG. 25 is an exploded horizontal sectional view along the line 2525 in FIG. 24;

FIG. 26 is a perspective view of the locking element of FIGS. l925; and

FIG. 27 is an axial sectional View of the gear-locking member taken along the line 2727 in FIG. 25.

Referring now in greater particularity to the drawings, and first to FIGS. l-8, there will be seen a rotary snap switch identified generally by the numeral 20. The switch comprises a front or detent plate 22, an intermediate plate or bulkhead 24, and a back plate 26. The detent plate 22 is spaced forwardly of the bulkhead 24 by four relatively short spacers 28, and the 'back plate 26 is spaced a greater distance behind the bulkhead by four relatively long spacers 30 aligned with the spacers 28. Through bolts 32 extend through the detent plate, the spacers -28, the bulkhead 24, the spacers 30, and the back plate 26, the heads of the bolts being recessed or countersunk in the detent plate 22. Nuts 34 are threaded on the ends of the bolts.

The detent plate 22 is provided with a threaded bushing 36 which may be secured in place by conventional means such as brazing, or expanding or peening in position. The detent plate further is provided with a plurality of small holes 38 spaced along an arc concentric with the bushing 36. In the illustrative embodiment now under consideration, there are four such holes spaced at twenty degrees apart. The holes 38 comprise locking holes, as will be brought out hereinafter.

A driving shaft 40 extends rotatably through the bush ing 36 and to the rear of the detent plate 22. The driving shaft 40 may be rotated by any suitable or desirable means, including the usual manually engageable knob (not shown). The driving shaft is provided at its end with a reduced diameter tip 42. A driving plate or driver '44 is fixed adjacent/the end of the driving shaft on a section 46 of intermediate diameter, and preferably is held in place by brazing at 48.

The driver 44, as may be seen in FIGS. 5, 7, and 8, comprises a segment of a circular plate somewhat greater than a semicircle. The segment is cut off or defined by a terminating chord 46, and a driver finger or lug '48 extends rearwardly from the center of this edge in an axial direction. Diametrically opposite to the finger 48 the driving plate or driver 44 is provided with a cam slot 50. This slot tapers from a maximum width radially of the driver at the center of the slot, as at 52, to a minimum dimension at the opposite ends thereof. The ends are formed as circular arcs. The slot extends twenty degrees in either direction from the center thereof, in accordance with the twenty degrees spacing of the locking holes 38.

The switch further includes a driven shaft 54 journaled in the bulkhead 24 and back plate 26 coaxial with the driving shaft 40. The forward end of the driven shaft 54 is slightly enlarged at 56 and is provided with a counterbore 58. The counterbore receives the reduced extend ing end 42 of the driving shaft 40. A latch plate 60 is mounted immediately adjacent the enlarged section 56, and is secured to the driven shaft 54, preferably by brazing. The latch plate is spaced from the bulkhead by a washer 62. The latch plate 60 is a circular segment of somewhat greater extent than the driver 44, and has a forwardly extending driven finger 64 overlying the driving finger 48 on the driver.

A torsion spring 66 encircles the enlargement 56 of the driven shaft 54, and the opposite ends thereof at 68 and 70 respectively, project past the sides of the driving finger 48 and the driven finger 64, whereby normally to hold these two fingers resiliently in radial alignment. As will be appreciated, when the driving shaft 40 is turned, it causes the driver 44 to turn, and this acts through the torsion spring 66 to tend to drive the latch plate 60, and hence the driven shaft 54.

A cup 72 is mounted on the latch plate 60 diametrically opposite to the driven finger 64 by means of an integral stem 74 projecting through an aperture in the latch plate, and peened over. A plunger 76 is received in the cup 72, and comprises a hollow body 78 having a tapered or frusto-conical nose 80 with a cylindrical tip 82 extending therefrom, and of proper size to be received in any of the locking holes 38. A coil spring 84 is housed within the hollow body 78, and biases the plunger outwardly of the cup 72. Thus, the tip 82 is received in one of the locking holes 38, while the frusto-conical or tapered nose 80 is urged into the cam slot 50 of the driver 44.

Since the tip 82 is in one of the holes 38, then the latch plate and driven shaft cannot rotate immediately upon rotation of the driving shaft 40. However, when the driv- 7 the plunger back against its biasing spring 84, thereby retracting the tip 82 from the locking hole 38 in which it has been located. As will be understood, the rotation of several degrees of the driver relative to the latch plate has caused further tension to be placed on the torsion spring 66. Hence, as soon as the tip 38 has been withdrawn from the associated locking hole, the torsion spring 66 snaps the locking plate back into rotational alignment with the driver, and the driven shaft 54 is rotated. The initial offset of the driver relative to the latch plate, and the subsequent rotation of the driven shaft 54 amount to twenty degrees, the spacing between locking holes 38, and the extent of the cam slot 50 on either side of the center thereof.

As may be seen in FIGS. 1 and 2, there is a plurality of identical switches 86 spaced along a pair of supports 88 extending between the bulkhead 24 and the back plate 26. These switches are of the type having push buttons 90 for operation of the switches. A like plurality of levers 92 is pivoted on a pin or shaft 94 substantially on a level with the driven shaft 54. The levers extend out across the switches 86 and lie on top of the push buttons 90. A plurality of set screws 96 is threaded through suitparticularly in FIG. 1, the second set screw from the front is engaging the corresponding lever 92 to close the associated switch 86. The front set screw 96 is in the foreground, and it will be understood that this set screw will engage its corresponding lever 92 if the driving shaft 40 is turned in a clockwise direction, as viewed from the front of the switch. Similarly, the third and fourth set screws are in the background, spaced respectively twenty degrees, and will engage the corresponding levers 92 if the driving shaft is turned twenty degrees or forty degrees in a counterclockwise direction.

Thus, it will be apparent that as the drive-n shaft moves with a snap action, in the manner heretofore described, the various switches 86 are opened .or closed with a snap action.

Reference now should be had to FIGS. 9, 10 and 11, wherein a modification of the invention is illustrated. Most of the modification is similar to the previously disclosed embodiment. Similar numerals are utilized with the addition of the sufi'ix :1. Accordingly, repetition of the description of such parts is believed to be unnecessary. The differences reside in the type of switch contact arrangement, and in the degree of rotation. Thus, the-re are four locking holes 38a in the detent plate 22a, these holes being spaced at ninety degrees, and being concentric with the driving shaft 48w. correspondingly, the cam slot 50a in the driver 44a is 180 in iarcuate extent. At the center thereof, as indicated at 52a, the cam slot is of maximum width. The width remains constant throughout most of the extent of the cam slot, but adjacent the opposite ends, as indicated at 100, the slot tape-rs to a minimum dimension at the ends 102, such dimension being just sufiicient to receive the tip 82a of the plunger 76a.

On the back plate 26a, there is provided "an insulating plate 101 having four fixed contacts 103 thereon spaced arcuately at ninety degrees. The movable switch arm 104 is carried by an insulating fitting 106 on the end of the driven shaft 54a, and is engageable with any of the fixed contacts 103. A slip ring 105 is mounted on the insulating fitting 106 and is connected to or formed integral with the arm 104. A brush 107 r-i-des against the slip ring 105 to form electrical contact with the switch arm-s 104. As will be understood, the ninety degree extent of the driver allows the driving shaft to move substantially ninety degrees before the cam slot 50a unlocks the plunger 76a from one of the locking holes 380. Accordingly, the switch arm 104 moves ninety degrees within a snap action, quickly breaking away from one contact, and engaging the next, whereby to prevent burning or arcing.

From the foregoing it will be seen that there has been herein presented an improved snap switch mechanism of .a notary type, but adapted for controlling either a rotary switch or one or more switches of the push button type. The snap action mechanism of the switch insures rapid opening and closing of switch contacts, thereby largely eliminating arcing and burning of the contacts. Since the latch plate and the driven shaft are locked in position until such time as the driving shaft and driver have rotated substantially the distance through which the latch plate and driven shaft are to be rotated, it will be apparent that upon unlocking of the latter parts, they will immediately snap from one position to the next. Thus, there is not the slightest possibility of teasing the switch contacts by jiggling the driving shaft back and forth. Such jiggling will have absolutely no effect on the driven parts until such time as the arcuate movement necessary for unlocking has taken place, and the driven parts immediately move to the subsequent station and. are locked at that station.

In the embodiments of the invention .as heretofore shown and described, there has been a resilient spring drive between the shaft 40 and the shaft 54. The detent mechanism in each instance insures locking of the driven shaft 54 in position until after the driving shaft 40- has been turned a predetermined angular distance. However,

the detent principles of the invention have been found equally applicable to a snap switch in which the shaft is directly driven. As another way of looking at it, the driven shaft may 'be formed integral with the driving shaft. Other than the exceptions noted, the embodiment of FIG. 12 is similar to those previously described, and similar parts are used to identify similar numerals with the addition of the suffix b.

Thus, the driving shaft 40b is integral with the driven shaft 54b. The switch operators or levers 92b are in this instance driven by cams 96b. A knob 110 is fixed on the extending end of the shaft 40b.

A bushing 1'12 is rotatable on the shaft, being positioned by a washer 114 against a shoulder 116 of the shaft. The driven or latch plate 60b is secured to the bushing, as by brazing. The driving or driver plate 44b is fixed on the shaft 40b adjacent a shoulder 118 thereon, and against the back of the front wall 22b.

In operation, the knob 110 is turned to turn the shaft 40b, 54b, whereby the cams 96b operate the levers 92b to vary the condition of actuation of the various switches (not shown). Since the driven or latch plate 60b is at first secured against movement by the tip 82b of the plunger 76b fitting in one of the series of holes 38b, the spring 66b tends resiliently to 'hold the driver plate 44b, and hence the shaft 40b, 54b in its initial position. Thus, the shaft is turned against a spring force until it has turned far enough for the cam slot 50b to retract the plunger 76b against its internal spring 84b. The spring retarding force thus is removed, and the shaft moves to the next switch position, the tip 82b subsequently snapping into the next successive hole 38b. As will be apparent, the fact that the shaft is initially turned against a spring resistance tends to preclude accidental turning of the shaft, as by physical shocks, o'r inadvertent manual engagement of the knob. Furthermore, the shaft cannot come to rest in an intermediate position, or any other position off of a proper switch position, since the driven or latch plates will stop in position only at one of the holes 38b, and the shaft will be automatically aligned with the driven plate by virtue of the spring 66b acting between the driver plate 44b and the driven plate 60b.

A further embodiment of the invention is shown in FIGS. 13-16. This embodiment is substantially the same as that shown in FIG. 12, but is used alternatively thereto in accordance with different requirements, such as space requirements for the switch unit. Again, similar numerals are utilized to identify similar parts, the sufiix c being applied in this instance.

One essential distinguishing feature of this embodiment relative to the embodiment of FIG. 12, is that driving and latching mechanisms are not mounted on the shaft. Instead, a gear 120 (FIGS. 13 and 15) is fixed on the shaft forwardly of an intermediate supporting wall or web 240. The driving and latching mechanisms are radially offset therefrom, being mounted on a shaft 122 (FIGS. 15 and 16). The driver 440 is provided over a portion of its periphery with gear teeth 124 meshing with the teeth of the gear 120. Accordingly, the driver 440 is turned exactly in accordance with turning of the shaft 40c, 54c, but without being mounted on this shaft. Operation of the switch 200 of FIGS. 13-15 is similar to that of the embodiment of FIG. 12, except for the offsetting of the driving and latching mechanisms, as pre- "viously noted.

There is a further variation in connection with the last embodiment of the invention, as shown in FIG. 16. Thus, there is a solenoid 126 having a winding 128 on a coil form 130. The front portion of the coil form projects through the web 540 as at 132. The solenoid 126 further has a fixed core portion 134, by means of which it is mounted on the back wall 260. The solenoid also has a movable core portion or armature or slug 136 resiliently urged away from the fixed core portion by a spring 138 mounted in a recess in the front part of the fixed core portion 134. The armature or slug 136 carries a pin 140 which projects into .a recess 142 on the back side of the driver plate 440. In accordance with one practical embodiment of the invention, there is only one such recess 142. Hence, the pin 140 of the solenoid 126 tends to hold the switch in one particular predetermined position. The solenoid may be energized from some external source (not shown) whereby to unlock the switch from the predetermined position. Once the switch has been so unlocked, it may be moved from one to another of several positions of switch actuation, and will be locked by the solenoid pin only when returned to the aforesaid predetermined position. The extent of rotation of shaft 40c is limited by a disc 139 (FIG. 13) fixed on the shaft and having a relieved section cooperable with a stop pin 141 fixed on the front wall 22c.

Reference now should be had to FIGS. 17-27 in connection with an improved form of the invention. The invention in this series of drawings includes a case or housing 144 having a molded on bottom 146 of plastic material or the like. This material underlies a floor 148 in the casing which supports the individual switches 86d. Lead wires 150 from the individual switches project through the floor 148 and through the molded bottom 150. As will be understood, the molded bottom hermetically seals the case.

The embodiments of FIGS. 17-27 is in many respects quite similar to that in FIGS. 14-16, and also partakes of features of the previous embodiments of the invention. Thus, in order to avoid prolixity of description, similar numerals have been utilized with the addition of the suffix d. The driving shaft 40d and driven shaft 54d again are integral, and a knob d of more or less teardrop shape is shown on the end of the driving shaft for turning the same. The driven shaft 54d again is provided with cams 96d for operating the pivoted levers 92d for converting the rotary motion of the shaft 54a to reciprocating or oscillating motion for operating the pushbutton type switches 86d. Rotation of the driving shaft 40d again is limited by means of a disc 139d (see particularly FIG. 24) having a cut out section therein receiving a fixed stop pin 141d mounted in the front wall 22d. A driving gear 1200? is fixed on the driven shaft 54d, as in the last previous embodiment of the invention.

In the present instance, the driver 44d is provided with teeth 124d entirely around its periphery. The driver againis provided in its rear face with a recess 142d receiving a pin 140d extending from the slug or reciprocated member 136d of a solenoid 126d mounted on the intermediate wall 24d and on an intermediate wall or web spaced rearwardly thereof.

The solenoid 126d serves to latch the driver 44d at a predetermined rest or zero position. Hence, the switch unit cannot be switched or moved from this position until after the solenoid 126d has been energized. As will be apparent, a series of apertures 142d could be provided, whereby the solenoid would latch the driver in any predetermined position.

The present form of the invention is distinguished from the prior embodiment in the form of the latch mechanism. More particularly, the driver 44a. is provided on its face with radially disposed, arcuately spaced teeth 152 (see particularly FIGS. 23, 25, and 27). The teeth are arranged to present alternate crests 154 and valleys or roots 156. The teeth are higher at their radially outer ends as indicated at 158 in FIG. 27, and tapered to a minimum height at their radially inner ends as indicated at 160. The shape and size of the teeth are such as to result in two diametrically opposite plateaus 162. The presence of these plateaus does not interfere with the movement of the driver member since the degree of rotation thereof is limited by the disc 139d and pin 141d which limit the rotation of the shaft 40d, 54d.

Confronting the teeth 152 is a locking detent 164. The detent 164 comprises a rectangular block 166 (see 7 particularly FIG, 26) disposed diametrically of the driver 44d. The detent 164- is provided on the front face of the block 166 with .a wedge shaped tooth 168 running from end to end thereof. The tooth is configured to fit between adjacent teeth 152 on the face of the driver member 44a.

The detent 164 is mounted in a slide block 170 (see particularly FIG. 25) held on the back side of the face 22d by means such as screws 172 extending through the face and threaded into the slide block. The slide block is provided with a channel 174 receiving the base or block 166 of the detent 164, and is further recessed at 176 and 178 for receiving the driver member 44d and the face teeth 152 thereon. The stub shaft 122d receiving the driver 44d extends through the slide block 170, and through a central aperture 180 in the detent.

The detent 164 is provided on the back face thereof with a pair of recesses 182 spaced on opposite sides of the shaft opening 180. These recesses receive the front ends of a pair of helical springs 184, the rear ends of which are seated in complementary recesses 186 in the detent block 170.

The cooperation of the detent slide box, the detent plunger, the face teeth on the driver, and the locking pin for the driver is shown in somewhat exploded nature in FIG. 25. Normally, the parts are related as shown in FIGS. 19 and 20, and the various switches 86d are held in predetermined conditions of open or closed. When the solenoid 126d is energized to retract the pin 1400', the parts are capable of being moved. Turning of the knob 110d tends to rotate the driving shaft 40d and the integral driven shaft 54d. This tends to cause the gear 120d to rotate the gear toothed driver 4412!. However, such rotation is resisted by the spring pressure of the tooth 168 of the detent plunger. However, sufficient pressure on the knob 110d will cam the tooth 168 out of the valley between adjacent teeth, and over the intervening crest. As soon as the detent or detent plunger has passed such crest (it will be understood that it simultaneously passes a pair of crests on diametrically opposite sides of the driver) the springs force the detent tooth into the next succeeding valley, whereby to snap the driver from one rotational position to the next, the driven shaft 54d simultaneously being snapped to the next succeeding position through the gear teeth 124d and the gear 12nd. The cams 96d and levers 92d thus change the conditions of the individual switches in accordance with the shape of the cam, some of the switches being changed, and others remaining as before. In any event, the action is a snap action, which is highly desirable from a standpoint of switch contact life, and from a point of precisely controlling the operation of the device which may be connected to the individual switches 86d.

The particular detent mechanism just described has the virtue of impossibility of dead centering. Thus, the driver cannot dead center relative to the detent plunger, and hence the driving and driven shafts cannot be left in such position that the switches are anything but fully opened or fully closed. Accordingly, incorrect combinations of circuits cannot be made. The detent mechanism just described has the further desirable characteristsic of being able to develop rather heavy torque through the cam action of the detent tooth, as forced by the springs 184. This allows the switch unit to operate satisfactorily even though rather substantial friction might be developed in the moving parts, as through corrosion or extreme temperature or pressure variations.

Additionally, the switch unit has rather high inherent frictional resistance to movement. The various lever arms have a certain amount of friction about their mounting shaft, the bearings of the driving and driven shaft present a certain amount of friction, the cams and follower levers present friction (as well as the force necessary to close the switches 86d), and a certain amount of friction is introduced by the detent mechanism itself. All

of this friction and resistance to, rotation readily isovercome by a substantial margin through the use of the detent mechanism of FIGS. 17-27. Even if the operator were deliberately to try to place the operating knob in a middle position, the detent mechanism would positively shift the driven shaft in one way or the other to a definite switch position. Furthermore, as will be obvious, there is no chance for one switch position to be skipped inadvertently, since the detent mechanism tends to lock rather positively in any given position.

As will be apparent, the crests of the face teeth on the driver, and also the crest of the detent tooth 163 are quite sharp. As a result, full torque is developed immediately upon passing of a dead center position of the detent tooth and the driver face teeth.

Various changes in structure will no doubt occur to those skilled in the art, and will be understood as forming a part of this invention insofar as they fall within the spirit and scope of the appended claims.

I claim:

1. A snap action switch unit comprising base means, a plurality of push button type switches mounted on said base means in side by side linear array, a shaft, means rotatably supporting said shaft from said base means extending past all of said switches, a plurality of levers pivotally carried by said base means and each having a portion engaging a push button of a respective switch and having another part adjacent said shaft, a plurality of cam means axially spaced on said shaft and each engaging one of said levers, said cam means acting through said levers to determine the respective open and closed position of said switches, a rotary member rotatably carried from said base means and rotatable with said shaft, said rotary member having a plurality of face-type teeth of uniform height thereon, and a detent member spring pressed against said teeth axially of said rotary member and cammed axially away from said rotary member by said (teeth in succession, said detent member resisting rotation of said rotary member, and imparting a snap action thereto upon passing of a tooth crest.

2. A snap action switch unit as set forth in claim 1 wherein the detent member spans said rotary member and engages substantially diametrically opposite teeth.

3. A snap action switch unit as set forth in claim 2 wherein the detent member has a wedge shaped configuration confronting said rotary member and engaging the teeth thereof.

4. A snap action switch unit comprising base means, a plurality of push button type switches mounted on said base means in side by side linear array, a shaft, means rotatably supporting said shaft from said base means extending past all of said switches, a plurality of levers pivotally carried by said base means and each having a portion engaging a push button of a respective switch and having another part adjacent said shaft, a plurality of cam means axially spaced on said shaft and each engaging one of said levers, said cam means acting through said levers to determine the respective open and closed position of said switches, a gear on said shaft, 21 member rotatably mounted from said base means, said member having peripheral gear teeth meshing with the teeth of said gear whereby said member is rotated in timed relation with said shaft, said member further having deep uniform face type teeth extending in an axial direction, and a spring urged detent member engaging said face type teeth, said face type teeth camming past said detent member, whereby said detent member resists rotation of said rotary member and hence of said shaft, and imparts a snap action thereto as said face type teeth pass said detent member.

5. A snap action switch unit as set forth in claim 4 wherein the detent member spans said rotary member and is provided with a wedge configuration engaging said face type teeth on diametrically opposite sides of said rotary member,

References Cited by the Examiner UNITED STATES PATENTS 2,023,219 12/1935 De Reamer 200-70 10 4/ 1939 Hart 74527 3/1958 Bulgin W 200-17 10/1959 Brown 20065 X 7/ 1962 McCouch 74527 FOREIGN PATENTS 9/1949 France.

10 FRED C. MATTERN, JR., Primary Examiner.

F. E. BAKER, Assistant Examiner. 

1. A SNAP ACTION SWITCH UNIT COMPRISING BASE MEANS, A PLURALITY OF PUSH BUTTON TYPE SWITCHES MOUNTED ON SAID BASE MEANS IN SIDE BY SIDE LINEAR ARRAY, A SHAFT, MEANS ROTATABLY SUPPORTING SAID SHAFT FROM SAID BASE MEANS EXTENDING PAST ALL OF SAID SWITCHES, A PLURALITY OF LEVERS PIVOTALLY CARRIED BY SAID BASE MEANS AND EACH HAVING A PORTION ENGAGING A PUSH BUTTON OF A RESPECTIVE SWITCH AND HAVING ANOTHER PART ADJACENT SAID SHAFT, A PLURALITY OF CAM MEANS AXIALLY SPACED ON SAID SHAFT AND EACH ENGAGING ONE OF SAID LEVERS, SAID CAM MEANS ACTING THROUGH SAID LEVERS TO DETERMINE THE RESPECTIVE OPEN AND CLOSED POSITION OF SAID SWITCHES, A ROTARY MEMBER ROTATABLY CARRIED FROM SAID BASE MEANS AND ROTATABLY WITH SAID SHAFT, SAID ROTARY MEMBER HAVING A PLURALITY OF FACE-TYPE TEETH OF UNIFORM HEIGHT THEREON, AND A DETENT MEMBER SPRING PRESSED AGAINST SAID TEETH AXIALLY OF SAID ROTARY MEMBER AND CAMMED AXIALLY AWAY FROM SAID ROATRY MEMBER BY SAID TEETH IN SUCCESSION, SAID DETENT MEMBER RESISTING ROTATION OF SAID ROTARY MEMBER, AND IMPARTING A SNAP ACTION THERETO UPON PASSING OF A TOOTH CREST. 